This invention relates to electric lamps. More particularly the invention relates to electric lamps where a filament of the lamp is aligned with a focal point of a reflector.
PAR type lamps operate most efficiently when a filament coil of a light source is in a known position relative to the focal point of the reflector of the lamp. Known methods to fix the location of the light source and thus the filament relative to the reflector (or reflector housing) include using an insulating spacer and ceramic adhesives. This assembly technique is process intensive and results in filament tube reliability issues due to cement transfer onto a pinched end of the light source and mislocation of a heat shield, which can cause thermal cycle oxidation failures. Quality issues such as deviation from desired beam pattern, center beam intensity, and lumen output can also be prevalent with this type of fixing system.
An alternative method of fixing the location of the light source uses a metal disc in conjunction with metal eyelets. In this method, to assemble the lamp, a light source is inserted into an opening of a positioning member that is placed in engagement with a ledge of a protrusion. Thereafter, a force is applied to positioning member so as to deform it slightly rearwardly. After the force is applied to the positioning member a pair of eyelets are then mechanically fastened to the leads that will retain the deformation of the positioning member. After a period of time the assembly will “relax” so that a force remains on the positioning member.
Another alternative uses two metal eyelets crimped tightly to the base of the reflector housing. This alternative is highly dependent upon small variations and the conditions of openings in the base of the glass reflector. Furthermore, no positioning member is provided to facilitate positioning the light source in the reflector housing. Consequently, fixing the filament coil of the light source in a known position relative to the focal point of the reflector is difficult.